1. Field of the Invention
The invention relates to mud guards for truck and trailer wheels and more particularly to removable mud flap hangers of the cantilever type for such wheels.
2. Description of the Prior Art
Virtually all vehicles operated on public highways are required by state law to be equipped with means for intercepting mud, water spray, gravel, etc., thrown rearwardly by the vehicle's wheels, the purpose being to protect following vehicles from damage and from obscured vision which could cause accidents.
Trucks and trailers may satisfy this requirement by hanging mud flaps rearwardly of exposed wheels. Depending upon the size and number of wheels, the mud flaps may be as large as two feet wide and three feet long. They are generally constructed of a comparatively thick sheet of tough, resilient material for strength and are sufficiently heavy not to sail out rearwardly at high vehicle speeds. Many types of vehicles have no structure above the exposed wheels, so it is necessary to cantilever mud flap hangers outwardly from frame members inwardly of the wheels. The mud flap hanger alone is comparatively expensive, considering the frequency of replacement, and may cost about $60 per pair.
The mud flaps and cantilevered mud flap hangers are generally in exposed locations and are subject to considerable wear and abuse. For example, when used on trucks or trailers which haul logs, rocks, gravel, etc., and which are used extensively on rough, unpaved, non-public roads, the mud flaps, unless removed, may quickly be torn by objects thrown by the wheels or by obstructions and the hangers may be bent or broken by similar means. On many types of trailer trucks, notably the so-called "fifth wheel" types where forward portions of the trailer overhang rearward portions of the truck, front underportions of the trailer may contact the hangers on the truck when the vehicle vertically "jackknifes" in transition between a level surface and a steep ramp to a loading dock. If the hangers are not removed they may be broken, or may be bent to a degree allowing the mud flaps to drag on the tires.
Because of these and other problems, most cantilever-type mud flap hangers are constructed so that they can be removed when conditions which might give rise to damage to the hangers or mud flaps are anticipated, and so that they can later be reinstalled.
It has heretofore been necessary, however, for an operator to get in behind the wheels at which such removable mud guards are positioned, and often to get under truck structures, to effect disengagement of the hanger, for example to unbolt it or knock it loose. The operator must again get in behind the wheels or under the structure to reengage the hanger. Removing and replacing hangers in this manner is often a disagreeable and difficult task, as the mud guard, wheels and adjacent vehicle structure may be wet or covered with mud, snow or ice. More importantly, the operator may be injured in such an operation if the vehicle accidentally moves. Understandably, operators very often fail to remove the mud guards when they should be and the hangers and mud flaps are consequently damaged or lost and must be replaced.
Furthermore, in normal highway use, where mud flaps are required, cantilevered mud flap hangers are subject to continual up and down flexing at or near the vehicle attachment point, caused by the outhanging weight of the mud flap and the bouncing and pitching of the vehicle to which they are attached. When inner ends of the hangers are rigidly attached to the vehicle or where there are 90.degree. bends near the attachment point, such constant flexing rapidly causes metal fatigue and work hardening, with resultant breaking of the hanger often in only a very few months of service. Such breaking is very undesirable, not only because the lost hanger and mud flap must be replaced, but also because following vehicles may be hit by the falling hanger and mud flap or may cause an accident by swerving to miss a falling or fallen hanger and mud flap.
Some cantilever-type hangers are constructed having a helical spring portion adjacent to the vehicle attachment portion to partially absorb the vibrational flexing and to allow the hanger to "give" if it strikes or is struck by an obstruction. Producing such hangers is expensive, however, because special materials and heat treatment are required and, if the heat treatment is improper, the spring may be too weak and allow the mud flap to sag into contact with the wheels or the pavement, or the spring may be to brittle and break.
To the applicant's knowledge, no cantilevered mud flap hangers have heretofore been available which may be easily removed and reinstalled without an operator being required to get in behind wheels or under the vehicle to manually release or engage the hanger, which have near the attachment point, resilient regions for prolonging hanger life requiring no special materials or critical heat treating, and which are furthermore easy and economical to produce.